The present invention relates to a device and method for monitoring exposure to chemicals and pollutants, and more particularly, to a portable device for, and method of, accumulating chemicals and pollutants that are present in an ambient environment.
Polycyclic Aromatic Hydrocarbons (PAHs) are formed by the incomplete combustion of organic matter, and many of the compounds are known as carcinogens and/or mutagens. PAHs are found in the atmosphere in both gaseous and particulate states. Light (3-ring and 4-ring) PAHs occur primarily in the vapor phase, heavy (≧6-ring) PAHs are found predominantly in a particulate form, and 5-ring PAHs are commonly present in the vapor phase or as particulate matter. Temperature variations can promote a phase transition to either a gaseous state or a particulate state of various PAH species.
Prior-art techniques for sampling of vapor phase PAHs include removing PAHs from the air by solid cyclic oligosaccharides such as cyclodextrins, adsorption on an organic polymer (e.g., polyurethane foams) or on inorganic sorbents (silica gel or alumina), or cryogenic trapping. Extraction, chromatographic separation and optical detection follow the sampling [see Chemical Analysis of Polycyclic Aromatic Compounds, Vo-Dinh, T., ed., Wiley, N.Y. (1989)]. Effective extraction of PAH traces from the sampler is complex. Sample reduction in handling, incomplete extraction, and irreversible adsorption are known potential loss mechanisms for PAH compounds during the sample preparation step [see M. W. Sigrist, “Air Monitoring by Spectroscopic Techniques”, in: Chemical Analysis, J. D. Winefordner, ed., Wiley, N.Y. (1994)].
The monitoring of PAHs in the ambient air is a well-developed field in the U.S., Europe, and other industrialized areas. In particular, the monitoring of worker exposure to PAHs in the ambient air of the workplace is commonplace. A prevalent device for monitoring the exposure to chemicals is shown in FIG. 1A. The device includes a sorbent tube 10, a personal air pump 12, which is typically fastened to a belt, and a connecting tube 14 providing fluid communication between sorbent tube 10 and personal air pump 12. Personal air pump 12 draws ambient air through sorbent tube 10, which contains an active material for retaining various PAHs present in the ambient air.
Personal air pump 12 accompanies the worker throughout his entire work shift, in compliance with OSHA requirements. Personal air pump 12 is bulky (typically ˜14×12×5 cm), heavy (˜1 kg), and somewhat noisy. Consequently, such units are discomforting to wear, and are often used only when severe problems are indicated.
Moreover, the prior-art devices are costly, and the analytical techniques are both complicated and expensive. The cost of a typical pump is about $300, and each disposable sorbent tube costs about $2. The chemical analysis of each sorbent tube may take between 30 to 120 minutes, and requires a trained analyst. The instrumentation must be routinely calibrated, and a trained technician is required for ensuring proper sampling.
Extraction, chromatographic separation and optical detection follow the sampling stage. Such separate sampling and detection procedures result in numerous errors in estimating the contamination level.
Recently, particulate pollutants have been identified as extremely potent carcinogens and/or mutagens. The emission of particulate PAH traces into the atmosphere is a subject of growing concern. It will be appreciated by one skilled in the art that sorbent tubes are do not provide an adequate solution for the sampling of aerosols and particulate pollutants.
There is therefore a recognized need for, and it would be highly advantageous to have, a portable device for, and method of, monitoring chemicals and pollutants present in the ambient environment, which overcome the manifest deficiencies of the prior art. It would be of particular advantage to have a device that is light and compact, robust, inexpensive, and provides accurate results. Finally, it would be highly advantageous to have a device that is suited for the sampling of aerosols and particulate pollutants.